Lua - printTable - print tables on stdout or write into files

printTable.lua

--[[
A simple function to print tables or to write tables into files.
Great for debugging but also for data storage.
When writing into files the 'return' keyword will be added automatically,
so the tables can be loaded with 'dofile()' into a variable.
The basic datatypes table, string, number, boolean and nil are supported.
The tables can be nested and have number and string indices.
This function has no protection when writing files without proper permissions and
when datatypes other then the supported ones are used.
--]]

-- t = table
-- f = filename [optional]
function printTable(t, f)

   local function printTableHelper(obj, cnt)

      local cnt = cnt or 0

      if type(obj) == "table" then

         io.write("\n", string.rep("\t", cnt), "{\n")
         cnt = cnt + 1

         for k,v in pairs(obj) do

            if type(k) == "string" then
               io.write(string.rep("\t",cnt), '["'..k..'"]', ' = ')
            end

            if type(k) == "number" then
               io.write(string.rep("\t",cnt), "["..k.."]", " = ")
            end

            printTableHelper(v, cnt)
            io.write(",\n")
         end

         cnt = cnt-1
         io.write(string.rep("\t", cnt), "}")

      elseif type(obj) == "string" then
         io.write(string.format("%q", obj))

      else
         io.write(tostring(obj))
      end 
   end

   if f == nil then
      printTableHelper(t)
   else
      io.output(f)
      io.write("return")
      printTableHelper(t)
      io.output(io.stdout)
   end
end

@csm4502 I finally had the time to try with Lua 5.1.5 and I had no issues. Also tried with Lua 5.3 and it works as well.

If you find the issue let me know what it was. Thank you.

Hi @marcotrosi. I need your help.
I apologise if I am doing something really wrong but I have just started using lua files. I am trying to use a code to transfer a Lua table into another file.

When I run "printTable.lua using Lua53, I am getting the following as seen in the photo:

Do I need to copy the contents of the file with the table to yours? (it has only a table stored in it)
Am I using your file correctly just running straight with Lua 5.3.5?

Hi @marcotrosi. I need your help.
I apologise if I am doing something really wrong but I have just started using lua files. I am trying to use a code to transfer a Lua table into another file.

When I run "printTable.lua using Lua53, I am getting the following as seen in the photo:

Do I need to copy the contents of the file with the table to yours? (it has only a table stored in it)
Am I using your file correctly just running straight with Lua 5.3.5?

Hi @Believe82,

you can copy my printTable() function for example to your Lua script and use it there.

for example assume you have file named myLuaScript.lua

<copy paste function here>

-- create a table
YourTable = {1,2,3}

-- print the table using my function
printTable(YourTable)

and then run the script in the shell with ...

lua myLuaScript.lua

if you need more help join me on Telegram

https://t.me/LuaLang